This invention relates to a process for pattern dyeing of textile materials whereby improved pattern definition may be achieved. More particularly, the invention relates to a process for pattern dyeing textile materials in which dye migration across color boundaries is inhibited by forming a chemical coordination complex between components of a dye solution and components of a textile pretreatment solution.
Textile materials have heretofore been pattern colored with natural and synthetic dyes by numerous processes, such as transfer printing, jet dye injection, screen printing and the like. Further, such processes have been employed to print a color decoration on the surface or surfaces of the material in definite repeated forms and color to produce a pattern. While such prior art dyeing processes have met with success, problems have nevertheless been encountered in the pattern dyeing of textile substrates. For instance, when pattern dyeing textile materials, problems have often been encountered in that the repeating units of a pattern are not sharply defined, frosting occurs on the dyed material, and the color is not uniform throughout the dyed textile material. Many of these problems have been thought to result from undesired migration of the dyestuff after it has been applied to the textile material but prior to its actual fixation to the textile material.
In the context of this invention, dye migration is the movement of the dye molecules from one discrete location on the textile substrate to another. Dye migration can be caused by either dye diffusion through the liquid phase (before fixation to the textile substrate) or through capillary action where the dye moves with the liquid phase. The liquid phase is the dye solution being added in pattern form to the textile substrate.
Dye diffusion is the act of a dye molecule moving from an area of high dye concentration to an area of low dye concentration. Capillary action is the flow of a liquid (liquid phase) containing dye spreading through the capillaries of a textile substrate (cylindrical surface). The capillaries are formed as voids between the fibers forming the yarn as well as between the yarns which form the substrate.
Both dye diffusion and capillary flow are unfavorable in pattern dyeing when acting to convey dye molecules across color boundaries, which form the pattern, into adjacent areas of unlike color. Measurable migration of one color into another, either objectively or subjectively (visually), causes a loss of sharpness. A sharp pattern may be defined as having precise boundaries between adjacent colors and by an absence of measurable dark color encroachment into a light color area.
Frosty dyeing is defined as the presence of undyed fiber or filament in a presumed 100% single color area of a pattern. For example, a black area would look grey because of undyed fiber. The dyeing is said to be frosty.
Levelness is defined as a dye concentration (color depth) difference in a 100% single color area of a pattern. That is a solid color will look mottle or uneven if the dyeing is unlevel.
Numerous attempts have been made to solve the abovementioned problems without much success. For instance, it has been suggested to reduce the dye migration problem by incorporation of an antimigration agent in a dye solution. Among the antimigrating agents known in the prior art are natural gums; poly (vinyl methyl ether/maleic anhydride) derivatives as disclosed in U.S. Pat. No. 3,957,427; melamine formaldehyde and urea formaldehyde resins as disclosed in U.S. Pat. No. 4,132,522; Kelgin RL (Kelco Co.); Superclear 100N (Diamond Shamrock); and the like.
The use of antimigration agents has found restricted application in the textile dyeing industry. Some agents merely increase the viscosity of a dye medium without controlling dye migration significantly. Other agents tend to coagulate dyestuff values and reduce color yield. Also, the selection of the quantity of antimigration agent to be employed can be critical, and consequently the control of dye medium viscosity may be difficult.
In order to obtain sharp and clear patterns when range dyeing textile goods, it is common practice to use high viscosity dye mixes, on the order of several thousand centipoise. Generally, these dye formulas will also include a surfactant to promote dye penetration into pile goods, such as carpet. The use of such high viscosity formulations, even when surfactants are used, tend to restrict the penetration of dye into the pile fabric. Furthermore, for some types of dyeing processes and dyeing machines, such as dye jet printing, use of high viscosity dye mixes is precluded by the very nature of the dyeing process/machine. For example, in certain types of apparatus for jet injection dyeing and printing of textile materials, dye mix viscosities must generally be below about 1,000 centipoise so as to be compatible with the liquid switches providing the patterning capability. However, the use of such low viscosity formulations tend to result in a loss of sharp and clear patterns due to dye migration.
Recently, one of the present inventors proposed a solution to the dye migration problem in a process for pattern dyeing of textile materials. Specifically, dye migration is controlled by the in-situ formation of a water-insoluble polymeric skin around individual dye droplets when the dye solution is applied to the textile material. The skin is formed by the ionic interaction of an anionic, water-soluble, organic component with a cationic water-soluble organic component at least one of which, and preferably both, organic components being polymeric. The anionic organic component may, for example, be an anionic biopolysaccharide, such as xanthan gum. The cationic organic component may, for example, be a cationic polyacrylamide copolymer or a quaternized ammonium salt. In practice, a first aqueous solution containing one of the organic component reactants is applied to the textile material. Thereafter, a second aqueous solution of at least one dye and the other organic component reactant is applied to discrete portions of the textile according to the desired pattern, whereby the in-situ reaction occurs. The textile material is then heated to a temperature sufficient to fix the dye to the textile material.
While very good results have been achieved with this process the suitable reactants are somewhat limited and still further improvements are desired.
Accordingly, it is a main object of this invention to provide a process for achieving attractive pattern effects on textile materials with improved sharpness, uniformity and color yield.
It is another object of this invention to provide an improved process for applying sharply delineated dye patterns on a flat textile material by controlling dye migration.
Another object of this invention is to provide a process for improving the sharpness of a pattern of dye applied to textile materials with a jet dyeing apparatus using a dye mix having a viscosity of less than about 1,000 centipoise.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.